Pulp screen



Nov. 13, 1951 w. F. MATHEwsoN 2,574,977

PULP SCREEN Filed Dec. 1o, 1941.8 s sheets-sheet 1 92p il. 92g 2 ATTO/Q/VE Y6 Nov. 13, 1951 w. F. MATHEwsoN 2,574,977

'PULP SCREEN Filed Dec. l0, 1948 5 Sheets-Sheet 2 v /NVf/vTo/Q @yWMF/Q50 f MATHEWSO/v Nov. 13, 195] w. F. MATHEwsoN 2,574,9 77

PULP SCREEN I Filed Dec. 1o, 1948 I s sheets-sheet 5 /N Vf/V TOR\A//LFRED /v- MATA/EWSON ATTORNEYS @Y www@ f Patented Nov. 13, 1951 UNIPATE-N T oFFl 2,'5743977? PUIP SCREENS.

Wilfred-F. Mathewson, Boston,y Massy;Y ass'gnor to 1. MathewsonMachineWorks, Inc., Quincy, Mass.,` a .corporation of-.MassachusettsApplicatoxrzecember 10, 1948;' Serial No.A64,5.40-e

3 Claims.- (01.921435.)

In 'mylsUi Se: Patent No.; .2,450,838,,.October1 5, 1948;; therenislldescribedi.: andiifllustrated .1a.- paper pulp screen. comprising'.a casingiiavingean .inlet for .thei unscreened.' .pulp Landascreenedepulp gout?. let; and epulp screening means-within then-casingcomprising.. two= concentric cylindrical screen memberslproviding;.rbetweermthem canv annular clearance space of sufficient.sizezfforzthe ;fineeac= ceptable:lportionf` ofothezzzunscreened pulpto- .pass therethrougtn; but;.` of.'v unsuflicient;. size.i fori: the:coarse unacceptableiportion oflsuchpulptofpass therethrough:.v.Inlthefdevice 1of*A said fpatentzftheouteriscreenfmemberzisfaformedfon.;itscinnerrface witlra plurality of:vertically extending grooves; certainlopwhichigrooves constitute inletA'grooves andha've communication withuthesxinletztotthe casing andith'e:v remainder e of-1which1 groovesuconf stitute dischargegrooves andhavercommunicae tion'iwith the 'screenedepulp outlet. '..Thezscreeningvof :the .pulp is `.accomplished by floxvving: from they: inlet @grooves..to cthez-iclearance space aandY through said clearance space to thedischarge; grooves and thence to the screened-pulp'l outlet. Asfstatedfabovezthel .clear-ance: space is jsucliias. to allow `.theI .acceptableportion xofrthe.t ipulpfto pass therethrough. but wi1l preventthecoarsezorauna acceptableportionzof the .pulpjso=.pass..t:

Inathefdevice .of 'the' said patentA also thexouter screenfmemberehavingi the'. inlet :and: discharge grooves is stationary .while the: inner'screen-.membei' is rotatably mountedito "turn/about:r the axis offtheconcentric cylindersg..

The-device of the-present:applicationoperates on thesame principleascthatofftheabovefmem tioned Patent No. 2,450,838, A'but it:differsftrom the' devicezof .said patentin that: .thea .inlet :andldischargeggrooves are'. vformed in .the inner. 'rotate' able screenmemberaand saidngrooves arelendless grooves which.: extendlcircumierentialrly of :said: inner `member andcompletel-y. around-the'lattervl The-device of i the.. present 2 application. 1 also. diiers from that` of saidpatent.,iny rother particu? lars Ias will be.more. fully hereinafter set forth-.av

I have--illustrated` the, :present inventionas it might. .be` embodiedin aV laboratory mo'delfpulp screen rather than in:a `fullsize:commercial pulp screen-,. but the. constructionand operation .of thescreenelements isthe same in .bothr types of-fpulp screens.

lin-the. drawings Fig.4 lfis a sideview. of-a laboratorymodebpulpscreenembodying.theinvention,

Fig..2 is a frontvew thereof.,

Fig; 3is` a bottom ,plan view,

Fig.. .4 is a vertical-.sectionalivewthrough the casing,r and screenmembers taken on the line Fig. 5 is a similar. section with the innerscreen member. turnedil"l l.from the position .shown in Fig..6 is a.section on the line 6-6; Fig.- 4, i

Fig. .'IisV a section on the lirici- 1, Fig.' 4,

Fig'. 8 isa side view of theY outer screen member, and m Fig. 9 is afragmentary sideb elevation .ofthe inner screen member. t

In the. drawings ,l represents. the casing ofthe pulp screenwhich isprovidedat its' lower end withaninlet chamberZ to which the unscreened'pulpis delivered and is provided Aat its upper end withffa dischargechamber ..3 into which the screened pulp is delivered, Said dischargechamber having communicationwith a delivery piped for thescreenedfpulp.q The two concentric substan-v tially cylindrical. screenvmembers are indicated at 5 and 6,'5 being theouter. screenmember andfthe. inner screen member .which is located .within the outer. screenmember. .The two screen members are. substantially'.cylindrical andrthey are constructed .to form .between them .an annular clearance space1 'whichv hasa width suicient for the fine .acceptable ,portion ofthe.paper .pulpito pass therethrough. but which has an. insufficientdimension to allowthecoarse` unacceptable vportion .of suchpulp topass..

In .the present construction the outei-screen member 5 isstationarilymounted inthe casing. l., and theinnerscreen member is arotarymem ber, it beingmounted on and rotated by a shaft. The innerscreen member t? 'is provided. with one or more interior chambers4Hfwhich. open through thebottom thereof and thus communicate directlywith rthe inletchambenvofthe casingwbut have no communication Vwithfthe,discharge chamber-3 except. through ithe .clearance space and vthegrooves to be presently described...`

Saidinnermemberis also provided with one or..more additicnalinteriorchambersl which communicate. directly with the discharge,cham..A ber ..3of. the .casing through ports-orpassages I3 .formedin the top.oisaidinner screen mem-1 ber-.6, .said .chambersl having nocommunication withthe inlet chamber 2 exceptvthrough the grooves to .bepresently described and said clear-V ance space- The inner screenrmember6 is `formed with` a. plural-ityvof parallel,. endless grooves whichextend circumferentially .thereoif.andcompletelyetheref aboutvall.ofcwhichfgrooves open` into the clear.

r ance-space L A.

Certain of said grooves, those indicated at II, also communicate withthe interior chambers 9 as shown in Figs. 4 and 7, While the othergrooves, those indicated at I2, communicate With the other interiorchambers I as best seen in Figs. 6 and 5. During the pulp screeningoperation, the unscreened pulp which is delivered to the inlet chamber 2will flow into and lill the chambers 9. Said pulp will flow through theinlet grooves' II into the clearance space I and will pass through saidclearance space into the discharge grooves I2 from which the pulp isdelivered to the chambers I0 that communicate through openings orpassages I3 with the discharge chamber 3 of the casing.

Inasmuch as the clearance space I is so formed as to allow only the neacceptableV portion of the pulp to pass therethrough, the pulp which isdelivered to the discharge grooves I2 and thence to the chambers VIIIwill be only properly screened pulp.

The coarse unacceptable portion of the pulp Which cannot pass throughthe clearance space 'I will tend to accumulate at the mouth of the inletgrooves II, and in order to prevent such accumulation from clogging thescreen, I have provided means for periodically flushing each inletgroove.

For this purposer the outer stationary screen member is provided withone or more openings I4 situated to register `with each inlet groove II,said openings leading into a tailings-receiving chamber I5 with whichthe casing I is provided and which encircles the outer screen member v5.The openings I4 thus provide a communication between the clearance spaceI and the tailingsreceivng chamber I5. The portions of the outer screenmember 5 which are opposite or register with the discharge grooves I2are solid, the openings I4 being situated only opposite and in registerwith the inlet grooves I I. i

If at any time during the screening operation some of the coarseunacceptable portion of the pulp becomes clogged at the mouth of anyinlet y groove I I, then when such obstruction comes opposite an openingI4 during the rotation of the inner screen member 6, such obstruction orunacceptable portion of the pulp Will flow through the opening I4 intothe chamber I5 from whence it is delivered through the delivery pipe I6.

Since the inner screen member 6 is continuously rotating, each inletgroove II will be continuously ushed so as to prevent any of the coarseand unacceptable portion of the pulp from accumulating in the clearancespace and inter ferring with the screening operation. j

In the construction shown the outer screen member 5 is provided withthree flushing openings I4 for each rinlet groove, but the number ofsuch openings may be varied without departing in any Way from theinvention.

The rotary inner screen member 6 may be Supported within the outerscreen member 5 in any suitable or approved way. As herein shown thereis provided a step bearing I'I carried by the casing I and on which thescreen member 6 rests as best seen in Figs. 4 and 5. This -step bearingis shown as screw threaded through the bottom I8 of the casing I andhence can be adjusted vertically as required. It is held in its adjustedposition by the set nut I9.

In the illustrated embodiment of the invention, while the screen members5 and 6 are substantially cylindrical, yet Vthey are shownv as slightlytapered, the screen member 6 havinga slightly smaller diameter at itsupper end than at its lower end. An advantage of this construction whenused with the adjustable step bearing I'I is that by adjusting saidbearing vertically, the dimension of the clearance space I can bechanged to suit different pulp screening requirements.

As stated above, the present invention is shown as it might be embodiedin a laboratory model pulp screen, which, of course, is built on a muchvsmaller scale than a full size commercial may chine.

In the device herein shown the casing I is secured by abracket 2l] to abacking board y2 I that may be secured to the wall of a building. 4Thislbacking board ZI also supports a motor 22, the shaft of which isconnected With lthe shaft 8 of the inner screen member 6 through areducing gearing 3l. The power output shaft 23 of the reducing gearingis connected with a shaft 8 through a universal joint 24.

25 indicates a supply tank containing unscreened pulp which may also bemounted on the backing board 2I above the motor. The unscreened pulp isdelivered from the tank 25 to the inlet chamber 2 through a suitablepipe connection 26, 21 that leads into the chamber 2. The pipe 26 mayconveniently be provided With a shut off valve 28.

With this construction the unscreened pulp is delivered to the chamber 2at the bottom of the casing and then flows upwardly through the interiorchambers 9 and through the inlet grooves II into the clearance space.The screened pulp which is delivered through the discharge grooves I2passes through the clearance space into the interior chambers I0 andthen ows upwardly through the passages I3 to the discharge chamber 3 andthrough the discharge pipe 4.

The casing I may be provided with any suitable bearing 29 for the shaft8 and will preferably also be provided with any usual liquid seal 30.

I claim:

1. A pulp screen comprising a casing having an inlet for unscreenedpaper pulp and a screened-pulp outlet, two concentric substantiallycylindrical screen members located Within the casing and providingbetween them an annular clearance space of sufficient size for the ineacceptable portion of the unscreened pulp to pass therethrough, but ofinsufficient size for the coarse unacceptable portion of such pulp topass therethrough, the inner screen member having in its peripheral facea plurality of parallel, endless grooves extending circumferentiallythereof and completely thereabout, certain of said grooves constitutinginlet grooves and the remainder constituting discharge grooves, saidinner screen member having provision for connecting the inlet groovs 'tothe casing inlet and also for connecting the discharge grooves to thescreened-pulp outlet, the outer screen member having a plurality ofopenings communicating with the clearance space, one opening beingsituated opposite each inlet groove, and means to rotate the innerscreen member, said openings in the outer screen member providing forflushing away the unacceptable portion of the pulp.

2. A pulp screen comprising a casing having an inlet for unscreened pulpand a screenedpulp outlet, two concentric screen members located withinthe casing and providing between them an annular clearance space ofsuiiicient size for the line acceptable portion of the unscreened pulpto pass therethrough but of insuicient size for the coarse unacceptableportion of such pulp to pass therethrough, the inner screen memberhaving an interior chamber which communicates with the casing inlet andanother chamber which communicates with the screened-pulp outlet, saidinner screen member also having a plurality of endlessv groovesextending circumferentially thereof and completely thereabout, all ofwhich grooves open into the clearance space and certain of which groovesconstitute inlet grooves and open into the rst mentioned interiorchamber and the remainder of which grooves constitute discharge groovesand communicate with the other interior chamber. and means to rotate theinner screen member.

3. A pulp screen comprising a casing having an inlet chamber at itslower end to receive unscreened pulp and also having a discharge chamberat its upper end to receive screened pulp, two concentric screen memberslocated Within the casing between the inlet chamber and dischargechamber, said screen members providing between them an annular clearancespace of sufficient size for the fine acceptable portion of theunscreened pulp to pass therethrough but of insuiicient size for thecoarse unacceptable portion of such pulp to pass therethrough, the innerscreen member having an kinterior chamber which is open at its lower endto the inlet chamber of the casing and also having another interiorchamber which is open at its upper end to the discharge chamber of thecasing, said inner screen member further having a plurality of endlessgrooves extending circumferentially thereof and completely therewlabout, all of which grooves are open to the clearance space and certainof which grooves constitute inlet grooves and communicate with the firstmentioned interior chamber and the remainder of which grooves constitutedischarge grooves and communicate with the other interior chamber, andmeans to rotate said inner screen member.

WILFRED F. MATHEWSON.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,185,794 Haug June 6, 19161,821,684 Wiener Sept. 1, 1931 2,450,838 Mathewson Oct. 5, 1948 FOREIGNPATENTS Number Country Date 218,036 Great Britain July 3, 1924

